This morning when I started up my computer, it was set to lower than usual resolution (1024x768 vs 1920x1200) and no sound output for the monitor was available. It turns out it no longer recognizes the monitor as Dell U2413, but instead as "non PnP". The monitor is connected via HDMI.

Also, my Apple keyboard which was connected to the monitors internal USB hub was completely dead. The mouse and webcam, which are also connected to the monitors USB hub, still work.

I've tried using the DisplayPort instead of HDMI but that gives no picture at all.

I did the monitor self test (holding buttons 1 and 5), and the panel works perfectly with all the colors.

Is the monitor broken?